TGF-β1信号通路调控重离子辐射旁效应中microRNA表达的作用机制及归芪益元膏干预研究

Heavy ion is the optimal ray of tumor radiotherapy at present. But when tumor is radiated by heavy ion, the health organizations around the tumor are damaged by heavy ion radiation induced bystander effects. It includes many biology endpoints such as DNA damage etc. So it is a vital problem demanding prompt solution now whether an ideal biomarker is found to estimate the risk of radiation induced bystander effects in vivo and an effective drug defending radiation is researched and developed or not. Our researches in early days show that Gui Qi Yi Yuan Ointment can improve the pathological damage of the lung of the rats damaged by radiation induced bystander effects and protect peripheral blood. It can control the expression of signal factors in serum such as TGF-β1 and so on. It can alleviate DNA injury and make cell cycle be in normal progress. It also can regulate and control the expression of apoptosis genes. We speculate that microRNA in the circulating blood is perhaps the drug target which Gui Qi Yi Yuan Ointment protects and defends the damages caused by radiation induced bystander effects. In order to verify the hypothesis we plan to make the rat model of radiation induced bystander effects in vivo by radiating the right lung of the rats with heavy ion meanwhile covering the rest of the body with lead shielding. By filtrating and analyzing the identical microRNAs of differently expression in circulating blood and the double lung tissues, the influence of TGF-β1 signaling pathway on the expression of the microRNAs will be observed. And Gui Qi Yi Yuan Ointment will be used to intervene. The regulating effects on TGF-β1 signaling pathway and the microRNAs and the mechanism of action will be analyzed. It can provide the new ideas and methods to the study of defending the damage caused by radiation induced bystander effects with Traditional Chinese medicine.

重离子是目前最理想的肿瘤放疗射线，但重离子照射肿瘤时，可对病灶周围组织产生辐射旁效应，包括DNA损伤等诸多生物学终点。因此，能否找到一种理想的生物标志物来评估体内旁效应风险，研发有效防护药物是目前亟待解决的关键问题。我们前期研究发现，归芪益元膏可以改善旁效应大鼠肺部病理损伤，保护外周血象，抑制血清中TGF-β1等信号因子表达，减轻DNA损伤，保证细胞周期正常进行，调控凋亡基因表达。我们推测循环血microRNA可能是归芪益元膏防护重离子辐射旁效应损伤的药靶。为证实该假说，我们拟用重离子照射大鼠右肺部建立体内旁效应模型，通过筛选分析循环血及双肺中差异表达一致的microRNA，观察TGF-β1信号通路对该类microRNA表达的影响，并用归芪益元膏干预，探讨其对TGF-β1信号通路及该类microRNA的调控作用及机制，为中医药防护重离子辐射旁效应研究提供新思路、新方法。

在放射医学方面，重离子（12C6+）束由于具有传能线密度高、相对生物学效应高、束流位置可精准定位且低氧依赖性，被广泛应用在放射疗法中。但随着放射疗法的实施，辐射所产生的活性氧、电解质会对人体造成更大范围及更长时间的损伤，接受放疗患者的病人在利用电离辐射杀死肿瘤细胞的同时，会导致其正常的细胞、组织受到损伤，电离辐射对人体的伤害，使得更多的正常细胞及组织受累，引发二次损伤甚至癌症的发生。.通过12C6+束辐射归芪益元膏干预大鼠的右肺，其余铅皮屏蔽，建立辐射损伤模型，检测miRNA表达变化以及寻找TGF-β/Smads信号通路调控的靶基因，并预先用归芪益元膏干预，研究TGF-β/Smads信号通路各蛋白在辐射旁效应中的作用机制，并检测照射后不同时间点下，其辐照右肺及未照射的左肺、肾、脾、大肠等旁效应变化，观察、检测、探讨归芪益元膏干预后大鼠的旁效应损伤防护机制。.研究结果发现，其右肺受照射后，其脏器均呈现不同程度的损伤，其中miRNA21、Let-7i与TGFβ/Smad信号通路的激活联系紧密，并引入TGF-β受体抑制剂后，部分miRNA出现异常表达，间接证明了TGF-β/Smads信号通路在重离子辐射旁效应中的作用机制及对辐射旁效应中差异表达miRNA具有调控作用。同时归芪益元膏可通过抑制TGF-β/Smads信号通路的激活，能有效防治辐射及辐射导致的旁效应损伤。而TGF-β1及其通路中的蛋白随辐射时间的延长，其表达量有不同程度的升高，TGF-β1 /Smads信号通路的表达也存在着一定的时间效应。